This invention is concerned with a machine for performing a progressive operation on marginal portions of a shoe in the manufacture thereof comprising a shoe support for supporting a lasted shoe such that the shoe bottom is positioned in a desired relationship with a height datum of the machine, a tool support arrangement by which a tool holder is supported for pivotal movement about a first axis extending transversely of the bottom of a shoe supported by a shoe support, first drive means for effecting relative movement between the shoe support and the tool holder in directions extending lengthwise and transversely of the bottom of a shoe supported by the shoe support, whereby a tool supported by the tool holder can be caused to follow the plan contour of such shoe bottom, second drive means for effecting relative movement between the shoe support and the tool holder in a direction extending heightwise of the shoe bottom and thus for varying the relationship between a tool supported by said holder and said height datum whereby, as relative lengthwise and transverse movement takes place as aforesaid between the shoe support and the tool support arrangement, such tool can be caused to follow the height contour of the shoe bottom, and third drive means for effecting pivotal movement of the tool holder about said first axis to maintain an operating surface portion of a tool supported thereby in a desired angular relationship with the surface of the shoe bottom as such tool is caused to follow the plan and height contours thereof as aforesaid.
One such machine, for performing a roughing operation on marginal portions of shoe bottoms, is disclosed in EP-A0091321, while a similar machine, but for the progressive application of adhesive to marginal portions of shoe bottoms is disclosed in EP-A0276944.
In the operation of the former of these two machines the roughing tool is a radial wire brush which essentially lies in a plane extending heightwise of the marginal portions of the shoe bottom being roughed thereby, the arrangement being that this plane can be tilted, about the axis extending transversely of the shoe bottom, in order to maintain it normal, or substantially normal, in a direction extending transversely of the shoe bottom, to the portion of the surface of the shoe bottom at the region of engagement of the tool with the shoe.
In the latter machine referred to above, on the other hand, the adhesive-applying tool is constituted by a rotary brush of the "end mill" type, said brush surrounding a nozzle outlet through which adhesive is supplied, and the arrangement being such that, as the tool is caused to operate progressively along the shoe bottom, the rotating brush serves to spread the adhesive, giving a clearly defined edge adjacent the edge of the shoe bottom. The machine thus operates satisfactorily, especially on shoes having relatively low heels, but it has been found that, in the case of shoes the bottoms of which have pronounced contours in directions extending lengthwise and/or widthwise of the shoe, it is desirable to maintain the axis of rotation of the brush normal or substantially so to the portion of the shoe bottom upon which the tool is operating at any given time.
In addition to the two operations referred to above to be performed upon marginal portions of shoe bottoms, in some shoe constructions outsoles are used which incorporate an upstanding wall which is to be secured to side wall portions of the shoe, which portions thus in this case will require similar preparation treatment to shoe bottoms, or alternatively a shoe bottom unit may be directly moulded-on to the bottom of the lasted shoe in a injection-moulding process, again for which purpose at least side wall roughing and possibly the application of a primer or adhesive is again desirable. Customarily for carrying out such side wall treatment operations the shoe is presented manually by an operator to appropriate tools, but this is of course labour-intensive and time-consuming, and furthermore the quality of the operation is dependent upon the skill of the operator. Bearing in mind that, if the roughing operation or the primer or adhesive application extends beyond the region to which the sole unit is to be attached, the finished shoe will have an unsightly appearance, the skill of the operator in this case is of great importance.
There have therefore been proposals for rendering automatic the operation of side wall roughing, in particular using a commercially available, general purpose, robot device. Such devices are of course known comprising five or more axes by which a tool supported by a tool holder can be caused to operate upon a surface portion of a workpiece held by a work support, in such a manner that the contour in various directions of the surface is accommodated, while a given axis of the tool is maintained at a desired angular disposition in relation to the surface. In general, robot devices are so arranged as to emulate human configurations, and consequently it is customary to refer to wrists, elbows and the like to represent the various axes about which an articulated robot arm will operate. In adapting such a robot device for example for supporting a roughing tool for performing a progressive roughing operation on side wall portions of a shoe, however, it has to be borne in mind that customarily it is possible to "grade" the path of such a tool by reference to the overall length of the shoe, the various sizes of shoe in a given style customarily being graded according to known rules. Grading is of course possible using a multi-axis robot device, but in general such grading will require a good deal of computing, since modifications to the movement along one axis will invariably affect the other "downstream" axes, so that rather than perform a grading operation it may be preferable merely to teach each size and store the information. Such an approach will of course require a good deal more memory than where grading is possible.
For the same reasons, a general purpose robot device is unlikely to be satisfactory for use with an adhesive-applying operation to be performed upon marginal portions of the bottoms of a range of sizes of shoes.